For mining machines in general, and particularly for coal mining machines such as shown in U.S. Pat. No. 4,037,875 and for conventional continuous mining machines (see U.S. Pat. No. 4,047,763), it has been found desirable to provide the power source for rotating the cutting head completely within the confines of the cutting head. For instance, in U.S. Pat. No. 4,047,763 there is disclosed a mining head having a single support with a pair of cutting drums, one on either side of the support, and a separate power source for each of the cutting drums contained completely within each cutting drum, and a dual-stage planetary gear reduction means for transferring rotation of the motor shaft into rotation of the cutting drum. A cutting chain covers the support between the two cutting drums, only small radially outwardly extending portions of the supporting arm being provided, comprising the only non-rotating exterior portion of the cutting head. U.S. Pat. Nos. 3,290,096 and 3,288,536 disclose other prior art cutting heads having internal power sources. Both of these cutter heads include a pair of supporting arms with a single power source disposed between the arms for rotation of the cutting surfaces. In U.S. Pat. No. 3,290,096 the internal power source rotates in the opposite direction as the cutting drum, and connecting components are provided extending between a middle cutting drum portion and two exterior cutting drum portions on either side of the dual supports. Dual planetary gear reduction means are provided, and two non-rotating external exterior sufaces exist. U.S. Pat. No. 3,288,536 utilizes opposed windings on relatively rotatable parts interior of a cutting head shaft extending the entire length of the cutting head, with gearing connections to a plurality of surrounding cutter shafts, the gearing speeding up rotation of the cutter shafts compared to the central power source shaft.
While the prior art cutting heads with internal drive sources are generally useful, there has heretofore not been provided a cutting head with internal drive which requires only one supporting arm and only one motor for rotation of the drum and presents rotating cutting portions along the entire length of the cutting exterior thereof. Such a structure has been provided according to the present invention, however.
According to the present invention, a generally cylindrical drum for a mining machine or the like is provided. The cutting drum includes first and second generally cylindrical body portions spaced from each other along the longitudinal axis of the drum cylinder, each of the body portions having cutting projections formed on the exterior surfaces thereof. The power source is contained completely within the cylinder of the cutting drum and rotates the first body portion. Means are provided for effecting rotation of the second body portion upon rotation of the first body portion, said means including a cutting chain in operative association with both the body portions and operatively bridging the space therebetween.
Viewed in another manner, according to the present invention a cutting drum for a mining machine or the like is provided which comprises a generally cylindrical cutting surface having cutting projections formed thereon and having an axis of the cylinder and a pair of cylinder end faces. A single supporting arm for supporting the cutting drum extends perpendicular to the axis of the cutting surface intermediate the end faces thereof. A power source for effecting rotation of the cylinder cutting surface about the axis comprises a single motor disposed within the volume defined by the cylindrical cutting surface and a motor shaft, the motor having portions thereof extending axially on either side of the single supporting arm. Gear reduction means are provided for transferring rotation of the motor shaft into rotation of the cutting surface, the gear reduction means operatively connected to an interior portion of the cutting surface and to the motor shaft.
The cutting drum according to the present invention may be utilized with any type of mining machine but finds particular suitability in use with full face miners such as shown in U.S. Pat. No. 4,037,875, the disclosure of which is hereby incorporated by reference in the subject application. When utilized with a full face miner, it is desirable to have a capability of the cutting head of extending a portion of the cutting surface longitudinally along the axis of the drum to increase the possible effective cutting height of the drum.
Also according to the present invention, it is possible to achieve the necessary gear reduction with only a single stage planetary reduction gear means. The planetary reduction gear means includes a sun gear formed on the motor shaft, a planet carrier having three planetary gears mounted thereon, and a stationary ring housing concentric with the cutting surface and with gear means formed on the interior of the ring housing, the planetary gears being in operative association with the sun gear and the ring housing gear means. The planetary gears are relatively large compared to the sun gears so that the sun gear has gear surfaces of the planetary gears disposed adjacent thereto substantially around the entire 360.degree. circumference thereof.
It is the primary object of the present invention to provide a useful cutting head for a mining machine, the cutting head having a self-contained power source. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.